Liquid-filled transformers operate with current limiting fuses for protection. The fuses are mounted inside the liquid-filled tank and submerged in the liquid. In the event of a fuse failure, the transformer liquid is contaminated with carbon and other waste particles. Replacing the fuses is expensive and takes many days due to the nature of the liquid-filled transformers.
In order to replace fuses in a liquid-filled transformer, the transformer itself must be disassembled. The disassembly process involves waiting for the transformer to cool down, using a crane to remove the cover of the transformer and then extracting the core/coil of the transformer. Additionally typically several thousand gallons of transformer fluid that have become contaminated have to be drained, stored, transported, and disposed of accordingly. Then, in order to restore the transformer to functional status, a number of steps also have to be performed. The tank of the transformer must be cleaned and appropriately inspected. The core/coil have to be placed back inside the tank and then the fuses have to be replaced. Next replacement fluid must be transported to the transformer and used to refill the transformer. The cover of the transformer must then be reinstalled. Therefore, in the event one or more fuses blows in a current liquid-filled transformer, there are typically several days of labor involved in the inefficient and expensive process of replacing the fuses.